1. Field Of The Invention
This invention relates to a copper alloy which is excellent in hot rollability as well as adhesion strength of a plated surface thereof when heated, while having high strength and high platability.
2. Background Information
Conventionally, a copper alloy, which has a chemical composition consisting essentially by weight percent of 0.5 to 3 nickel (Ni), 0.5 to 2.5% tin (Sn), 0.05 to 0.9% silicon (Si), 0.1 to 2% of zinc (Zn), and the balance of copper (Cu) and inevitable impurities, has generally been used as a material of electrical parts such as terminals, connectors, and lead frames for semiconductor devices.
The known copper alloy has sufficient strength due to the component elements Ni, Sn, and Si and sufficient platability due to the component element Zn.
However, the known copper alloy is so low in hot rollability that when hot rolled the rolled body is likely to have defects such as ear cracks and surface cracks. To avoid this, hot rolling of the known copper alloy had to be carried out at a low reduction ratio. This, however, requires the hot rolling to be repeatedly executed, resulting in an increased total time period of operation. Even with such repeated hot rolling, the above-mentioned defects cannot be completely eliminated. To remove the defects, the hot rolled body has to be scalped in a considerable amount, and further cracked ears have to be slitted, thus making the manufacturing process complicated and decreasing the yield in the manufacture of electrical parts. Further, the known copper alloy has low adhesion strength of a plated surface thereof in that if the plated surface is heated at a high temperature, there can occur blisters in the plated surface.